Current Modular Automation Controllers (FIG. 1), such as PLCs, typically consist of a rack 10 with a backplane 11, a power supply 12, a controller 13, and one or more plug-in I/O modules 14. The modules typically consist of one or more printed circuit board assemblies (PCA) 15 with a plastic or metal housing. The housing provides protection to the PCA, possibly terminal block or connectors 6 for field wiring and possibly I/O indicators 17. The PCA is secured to the housing typically using screws. The I/O module 14 is placed in the rack, and mates with a connector 18 in the backplane 11. The module 14 may be secured by some means, such as screws to the rack 10.
This type of I/O module construction which is typical of current modular automation controllers requires that the mating connector to the backplane, field-wiring connector 16, and indicator LEDs 17, all be of right angle type. This makes manufacturing of such modules expensive, as most automatic assembly lines are not able to place these types of components automatically. Such automation controllers and their I/O modules therefore are relatively expensive. The less expensive automation controllers tend to be non-modular, i.e. the type and number of I/O is factory ordered.
In this construction, to provide higher field wiring density while keeping the I/O module as slim as possible, the LED indicators 17 are not placed next to the I/O connection points 16, making it inconvenient for the users. Further this requires that the LED Indicators be either of right angle type, or placed (straight or surface mount LEDs) on an additional small PCA that would be perpendicular to main board, or special LED indicator block that can be mounted on the main board. In any case it is more expensive than having surface mounted LED placed directly on a printed circuit board that ha all other components.
This invention takes a different approach to modular automation controllers. The new approach allows for modular controllers that are less expensive to manufacture.